Spark-plug



F. HACHMANN AND E. WILSON.

SPARK PLUG.

APPLICATION FILED MAY 28, |919.

1,361,328, Patented Dec. 7, 1920.

UNITED sTATEs PATENT oEElcE.

FREDERICK HACHMANN AND EDWARD WILSON, OF ST. LOUIS, MISSOURI, ASSIGNORS OF ONE-SIXTEENTH TO CHAUNCEY R. WATSON AND ONE-SIXTEENTH TO PHILIP E. MOODY, BOTH OF DETROIT, MICHIGAN, SEVEN TWENTY-FOURTHS TO DAVID M. HUTCHINSON, OF FERGUSON, MISSOURI, AND ONE-FOURTH TO HERMAN C.

STIFEL, OF ST. LOUIS, MISSOURI.

SPARK-PLUG.

Specification of Letters Patent.

Patented Dee. 7, 1920.

A Application tiled May 28, 1919. Serial No. 300,345.

T o all whom it may concern.'

Be it known that We, FREDERICK HACH- MANN and EDWARD WILSON, citizens of the United States, and residents of St. Louis,

State of Missouri, have invented certain new and useful Improvements in Spark- Plugs, of which the following is a specification containing a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

This invention relates to spark plugs and has for its primary object a spark plug, the primary electrode of which 1s constructed of two separate sections or parts, the one part having a condenser so as to give an intensified spark.

A further object is to construct a spark plug provided with a condenser so that the entire primary electrode together with the condenser may be removed for cleaning purposes, or in other words, to remove accumulated carbon which fouls the spark plugs.

In the drawings:

Figure 1 is a side elevation of our complete device.

Fig. 2 is a vertical cross section of the same.

Fig. 3 is a bottom plan view'of the plug.

Fig. 4 is an enlarged fragmental section of the two sections of the primary electrode made use of.

` In the construction ot our device, we provide a casing 5 which is preferably constructed of steel and which serves as the grounded electrode. This casing is provided With screw threads 6 by means of which the casing is secured within. the explosion chamber of aninternal combustion engine. Formed integral with the casing 5 and above the screw threaded portion 6, we form the wrench surface 7 which is preferably hexagonal in form so that the easing may be secured to the explosion chamber of an internal combustion engine. The casing 5 is further provided with a bore 8 and a screw threaded bore 9, the bore 8 being of less diameter than the bore 9 so as to provide a shoulder 10. Upon this shoulder 10 is placed a gasket 11 which is constructed of material which is both resilient and heat resisting, asbestos being preferablyv used.

Secured within the screw threaded bore 9 is placed a packing nut 12, this packing nut being provided on its exterior with the screw threads 13 and a smooth inner bore 14, the upper end of this packing nut being provided with wrench engaging surfaces 15 so that the same may be secured within the casing 5.

Within the casing 10 is a porcelain insulator 15 within which the electrode 16 is securely cemented and baked so that there will be no leakage of compression along the joining surfaces of the electrode 16 and the porcelain insulator 15. This electrode 16 projects above the top surface of the porcelain insulator 15 as indicated by the numeral 17 and is in the shape of a truncated cone so as to fit tightly within the recess 18 70 formed in the primary electrode 19 which is likewise secured in a orcelain insulator 20. This porcelain insu ator is secured in the packing or binding nut 12.

Between the packing or binding nut 12 75 and the porcelain insulator 2O is placed a washer or a gasket 21 which is also com posed of heat resisting and compressible material so as to prevent the leakage of gas between the insulator and the nut 12. 80

IVithn the porcelain insulator 20 is secured the primary electrode 19 which is cemented and baked therein in a manner well known to the art of spark plug construction and having its ends 23a extending 85 beyond the. insulator 20. The lower portion 23a of this electrode 19 is provided with a conical recess 18 to receive the end 17 of the electrode 16 therebyv making a continuous electric connection.

Surrounding the primary electrode 19 are placed a series of insulating washers 22 which separate the condenser disks 23 and gathering disks 24 of the condenser. The disks or washers 22 are also formed of insu- 95 lating material as is fully illustrated in Fig.

Over these disks are placed the condenser disks 23 and gathering disks 24, they being separated from each other, and around these disks and the insulator disks 22 is poured the molded mica 25.

After the condenser has been assembled and the molded mica poured around, the entire mass is turned and bored so that the bore 26 will fit snugly around the electrode 19 and the outer or turned circumference 27 will fit within the bore 14: of the packing nut l2. Both of these lits, that is the fit around the primary electrode 19 and within the bore of the acking nut, are termed driving or force fits, so that there will be no tendency of dropping out, and it will be necessary to destroy the condenser in order to remove the same from the packing or binding nut. It is to be understood, of course, that the molded mica which is forced into the binding nut is of slightly lar er diameter than the bore therein, and t at portion which surrounds the primary electrode is of slightly less diameter than the electrode, so as to form a perfect electric connection and leav'e no gapbetween the electrode and 'the gathering plates, or the -grounded electrode and the condenser plates.

In the grounded electrode is seated awire o r electrode 27 which is brought in close proximity' with the wire or electrode 16, the wires 16 and 27, however, not touching, so that when the electric current is passed through the plug, the spark will pass between the wires 16 and 27 causing an eX- plosion in the ignition chamber.

When it is desired to clean vthe spark plug, it is only necessary to remove the nut 12 together with the condenser, andthe porcelain insulator and its electrode can be lifted out without removing the casing from the engine cylinder, or in case the primary conductor 16 becomes burnt out, it is only necessary to insert a new lower porcelain member or if the electrode 27 becomes worn out, a new casing can be supplied.

The upper end of the electrode is provided with screw threads 28 which project beyond the porcelain insulator 2O thus allowing the nut 29 to be securely seated on the insulator and the binding nut 30 to secure the electrical conductor between it and the nut 29, thus forming an electrical connection between the source of energy and the primary electrode.

Having fully described our invention, what we claim is:

1. A spark plug comprising a casing adapted to be attached to an engine cylinder, said casing answering as a rounded electrode, a primary electrode, an a series of insulated metallic plates forming an electric condenser in electrical contact alternately with said primary electrode and the grounded electrode.

2. A spark plug comprising a screw threaded casing adapted to be inserted in an engine cylinder, an electrode secured to said casing, a separable primary electrode mounted in said casing and insulated therefrom, and a series of conducting plates in\ sulated from each other forming a condenser in alternate electrical contact with the primary electrode and first mentioned electrode, saidl condenser being detachably mounted in the casing.

3. A spark plug comprising a screw threaded casing adapted to be attached to an engine cylinder, an electrode carried thereby, a porcelain insulator removably mounted in said casing, an electrode carried by said porcelain insulator, a second porcelain insulator, an electrode secured therein, a condenser in electrical contact with said last mentioned electrode, and a packing nut for securing the casing, the orcelain insulators and the electrodes carr1ed by said insulators together.

In testimony whereof we have signed our names to this specification, in the presence of two subscribln witnesses.

FRED RICK HACHMANN. EDWARD WILSON. Witnesses:

ELIZABETH CARTALL, WILTER C. STEIN. 

